Controller for electric motors



April 12, 1932. R. G. LOCKETT CONTROLLER FOR ELECTRIC MOTORS Filed June 21, 1930 Patented Apr. 12, 1932 PATENT OFFICE UNITED STATES RALPH G. LOC'KETT, OF WAUWATOSA, WISCONSIN, ASSIGNOR TO CUTLER-HAMMER, INC OF MILWAUKEE, WISCONSIN, A CORPORATION OF DELAWARE CONTROLLER FOR ELECTRIC MOTORS Application filed June 21,

This invention relates to controllers for electric motors, and while not limited thereto is particularly applicable to controllers for motor driven apparatus such as tire machines.

The patent to Frederick H. Oberschmidt, No.-1,549,921 of August 18, 1925, discloses a push button controller for motor driven machines of the aforesaid character which provides for operation of the driving motorin opposite directions selectively and for quick stopping of the motor at will or incidental to reversals. However, in some instances it has tions falling within the scope of the appended claims.

Referring to the drawing, the same illustrates a controller for a squirrel cage motor M, said controller including electromagnetic switches 1 and 2 for selectively controlling reverse power connections for the motor to effect plugging and running in either direction. The switches 1 and 2 are respectively provided with operating windings 1 and 2 and with auxiliary contacts 1 and 2 which are adapted as hereinafter set forth to complete maintaining circuits for said windings. The control means for switches 1 and 2 includes push buttons 3 and 4, each of which is provided with normally closed up contacts a and normally open down contacts I). The down contacts of switches 3 and 4 respectively provide for energization of switches 1 and 2. On the other hand, the up contacts of switches 3 and 4 are included in the maintaining circuits of switches 2 and 1, respectively, whereby depression of switch 3 tends to de- 1930. Serial No. 462,822.

energize switch 2, while depression of switch 4 tends to deenergize switch 1.

The controller also includes switches 5 and 6 to be included in the maintaining circuits of switches 1 and 2, respectively. Switches 5 and 6 comprise contact arms oscillatably mounted upon a shaft 7 but frictionally engaged therewith by slip couplings 8 whereby each of said arms may be oscillated by said shaft for engagement with stationary contacts a and b selectively, said contacts serving as stops for said arms to arrest the same independently of said shaft; The shaft 7 may comprise an extension of the motor shaft, as illustrated in the drawing, or a separate shaft operatively connected to the motor or to a reversing part of the driven machine whereby the arms of switches 5 and 6 will be engaged with their stationary contacts alternately upon successive reversals of the motor and the driven machine.

The reversin switches 1 and 2 are employed to plug t e motor M for stopping and the switches 5 and 6 are provided to maintain such switches energized when so employed until the motor is brought to rest. As aforestated, the switches 5 and 6 are in circuit with the operating windings of switches l and 2, respectively, and as will be understood both switches 5 and 6 are closed'throughout operation of the motor in either direction and function to maintain the plugging switch energized until the motor is brought to a standstill and then tends to rotate in a reverse direction, whereupon the switches 5 and 6 are immediately shifted to deenergize the plugging switch 1 or 2, as the case may be.

In addition to the aforedes cribed control means the controller includes a stop push button 9, a pair of treadle operated switches 10 and 11 and a pair of electromagnetic relays 12 and 13.

Each of the treadle operated switches 10 and 11 is provided with two sets of normally open contacts a and b and two sets of normally closed contacts 0 and (l and each of the relays 12 and 13 is provided with a set of normally closed contacts I) and two sets of normally open contacts 0 and d. As hereinafter set forth depression of either of-the switches 10 or 11 interru ts the maintaining circuits of switches 1 an 2, and depression of switch 10 energizes switch 1 and relay 12, while depression of switch 11 energizes switch 2 and relay 13. Also .as hereinafter set forth relay 12 is adapted to cooperate with switch 6 to effect plugging of the motor uponreturn of switch 10 to normal position, while relay 13 is adapted to cooperate with switch 5 to effect plugging of the motor upon return of switch 11 to normal position.

The operation of the aforedescribed controller and the circuit connections thereof willnow be more fully described. Depression of push button switch 3 completes an energizing circuit for reversing switch 1 extendm from line L through stop push button 9, through the up contacts 4 of push button switch 4, through contacts 11 of treadle switch 11, through the down contacts 3 of push button switch 3, and thence through the operating winding 1 of reversing switch 1 to line L On the other hand, depression of push button switch 4 completes the energizing circuit of reversin switch 2, said circuit ex-- tending from line 1 through stop push button 9, through the up contacts 3 of push button switch 3, through contacts 10 of treadle switch 10, through the down contacts 4 of push button switch 4, and thence through the operating winding 2 of reversing switch 2 to line L. Thus operation of the push buttons 3 and 4 selectively provides for energization of switches 1 and 2 as aforestated,

and in the following description it is assumed that switch 1 provides for operation of the motor in its forward direction while switch 2 provides for operation thereof in a reverse direction. 7

Switch 1 in closing engages its auxiliary contacts 1 and immediately upon starting of the motor in its forward direction switch 5 engages its contacts 5 whereupon switch 1 is maintained energized by a circuit extending from line L through stop push button switch 9, through up contacts 4' of push button switch 4, through contacts 11 of treadle switch 11, through contacts 5 of switch 5, through contacts 10 of treadle switch 10, through auxiliary contacts 1 of. reversing switch 1, through contacts 12 of relay 12 and through the operating winding 1 to line L Assuming energization of switch 1 for plugging following energization and deenergization of switch 2, it will be observed that the aforedescribed maintaining circuit for reversing switch 1 is completed through contacts 5 of switch 5, and as soon as the motor reverses switch 5 will be shifted to momentarily interrupt such circuit. Thus if push button switch 3 is released during pluggingof the motor, revers'ing switch 1 will be deenergized as soon as the motortends to operate in its forward direction. On the other hand, assuming retention of switch 3 until the motor begins to aeaaeae operate in its forward direction reversing switch 1 will remain closed until its maintaining circuit is interru ted by stop push button switch 9 or push button switch 4.

Depression of push button switch 4 to deenergize switch 1 also energizes switch 2, as aforedescribed, and if switch 4 is then released switch 2 will be maintained energized to bring the motor to rest, after which it will be deenergized by switch 6 in the same manner that switch 1 is deene ized by'switch 5. If, on the other hand, switch 4 1s held depressed until the motor begins to operate in its reverse direction the motor will continue to operate in a reverse direction pending deression of stop push button switch 9 or push utton switch 3. Upon response of revers ing switch 2 the same is maintained ener-, gized by a circuit extending from line L through stop push button switch 9, through contacts 3" of push button-switch 3, through contacts 10 of treadle switch 10, through contacts 6 of switch 6 if the motor is rotating in its forward direction, or contacts 6 of switch 6 if the motor is rotating in its reverse direction, throu h contacts 11 of treadle switch 11, throug auxilia contacts 2 of reversing switch 2, through contacts 13 of relay 13 and through the operating winding 2" to line L.

In connection with the foregoing it should be noted that uponfdepression of treadle switch 10 the contacts 10 thereof close to establish the aforedescribed energizing circuit for switch 1, while the contacts 10 thereof open to interru t the aforedescribed maintaining circuit or switch 2. Also it should be noted that upon depression of treadle switch 11 the contacts 11' thereof close to establish the aforedescribed energizing circuit for reversing switch 2 while the contacts 11 thereof open to interrupt the aforedescribed maintainlng circuit for switch 1. treadle operated switches 10 and 11 control switches 1 and 2 to provide for operation of the motor in opposlte directions selectively, and as is a parent, if the motor is operating in either irection and the power connections therefor are reversed by operation of either of the treadle switches the motor will be plugged during reversal.

Assuming that switch 10 is de ressed and that the motor operates in its orward direction, relay 12 1s then energized by a circuit extending from line L through sto 'push button 9, through contacts 4 of pus button switch 4, through contacts 11 of treadle switch 11, through contacts 5 of switch ,5, through contacts 10 of treadle switch 10, and thence through the operatingwinding 12' of said relay to line L. Upon response of relay 12 the contacts 12" thereof interrupt the aforedescribed maintaining circuit for reversing switch 1 and the contacts '12 of said relay shunt contacts 10 of Thus treadle switch 10, to thereby maintain relay 12 energized upon release of treadle switch 10. Assuming now that treadle switch 10 is released, the energizing circuit of reversing switch 1 is interrupted by contacts 10' and reversing switch 2 is energized by a circuit extending from line L through stop push button 9, through contacts 3 of push button switch 3, through contacts 10 of treadle switch 10, through contacts 6 of switch 6, through contacts 11' of treadle switch 11, through contacts 12 of relay 12 and thence through the operating winding 2* of reversing switch 2 to line L 'Thus upon release of treadle switch 10 the motor is plugged to bring the same to rest, and upon initial rotation of the motor in its reverse direction contacts 6 of switch 6 are disengaged to interrupt the aforedescribed maintaining circuit for relay 12. Relay 12 in returning to normal position opens its contacts 12 to interrupt the energizing circuit for switch 2, and the motor is thus stopped immediately I after plugging thereof.

Assume now that the motor is operating in its reverse direction, with treadle switch 11 depressed relay 13 is then energized by a circuit extending from line L through stop push button 9, through contacts 3 of push button switch 3, through contacts 10 of treadle switch 10, through contacts 6 of switch 6, through contacts 11 of treadle switch 11 and thence through the operating winding 13 of said relay to line L Upon response of relay 13 the contacts 13 thereof interrupt the aforedescribed maintaining circuit for reversing switch 2, while the contacts 13 of said relay shunt contacts 11 of treadle switch 11, to thereby maintain relay 13 energized upon release of treadle switch 11.

.Upon release of treadle switch 11 the contacts 11 thereof interrupt the energizing circuit for reversing switch 2, and reversing switch 1 is then energized to plug the motor by a circuit extending from line L through stop push button 9, through contacts 1 of pushbutton switch 4, through contacts 11 of treadle switch 11, through contacts 5 of switch 5, through contacts 10 of treadle switch 10, through contacts 13 of relay 13, and thence through the operating winding of reversing switch 1 to line L Reversing switch 1 is thus closed immediately upon release of treadle switch 11 to plug the motor and upon initial operation of the motor in its forward direction contacts 5 of switch 5 are opened to interrupt the aforedescribed energizing circuit for relay 13 and said relay in opening disengages its contacts 13 to interrupt the aforedescribed energizing circuit for reversing switch 1.

Thus the treadle operated switches 10 and 11 provide for inching operations of the driving motor in opposite directions selectively -by Letters Patent is:

1. The combination with an electric motor, of control means therefor including electroresponsive switches to eflect plugging and reverse operations of said motor, means operable by said motor for controlling said switches to deenergize each following plugging thereby, and two sets of control switches, one of said sets of control switches being operable to selectively control said reversing switches either subject to or independent of the influence of said means, and the other of said sets of control switches being operable to selectively control said reversing switches to effect inching operations of said motor in opposite directions and to effect plugging of said motor after inching operations subject to influence by said means.

2. The combination with an electric motor, of control means therefor including electroresponsive switches to effect plugging and reverse operations of said motor, switches operable by said motor for controlling said electroresponsive switches to deenergize each following plugging thereby, means for selectively controlling said reversing switches either subject to or independent of the influence of said switches, and means associated with said switches for selectively controlling said reversing switches to effect inching operations of said motor in either direction and to effect stopping of said motor by plugging after inching operations.

3. The combination with an electric motor, of electroresponsive reversing switches for selectively establishing reverse power connections for said motor, a pair of control switches, each movable out of a given normal position to close one of said reversing switches and to insure opening of the other of said reversing switches, means for establishing a maintaining circuit for each of said reversing switches upon closure thereof by one of said control switches, said latter means including switching means operable by said motor to interrupt and reestablish the maintaining circuits for said reversing switches upon reversals in the direction of operation of said motor, a second pair of control switches each movable out of a given normal position to close one of said reversing switches and to insure opening of the other of said reversing switches, and means associated with said latter control switches 'for controlling said reversing switches to effect pl of said motor upon return of either 2% said latter control switches to normal position, said latter means being under the control of said switchin means to effect arrest of said motor after p ugging thereof.

4. The combination with an electric motor, of electror'esponsi ve reversing switches for selectively establishing reverse power connections for said motor,'a air of control switches each movable out o a given normal position to close one of said reversing switches. and to insureopening of the other of said reversing switches, means for establishing a maintaining circuit for each of said revers tion to close one of said switches and eflect openin of the other of said switches, and a pair'o rela s cooperating with said control elements an adapted to control said switches to effect plugging of said motor upon return of either of said control elements to normal position. b

In witness whereof, I have hereunto subsubscribed my name.

' RALPH G. LOOKETT.

ing switches upon closure thereof by one of I said control switches, said means including switching means operable b said motor to interrupt and reestablish t e maintaining circuits for said reversing switches upon reversals in the direction of operation of said motor, a second pair of control switches each movable out of a given normal position to close one of said reversing switches and to insure opening of the other of said reversing switches, and a pairof electromagnetic relays controlled by said latter control switches and by said switching means, said relays providing for control of said reversing switches to effect pluggin of said motor upon return of either of sai latter control switches to r normal position and for arrest of said motor afterIplugging thereof.

.5. n a motor controller, the combination with an electric motor, of electroresponsive switches for selectively establishing reverse power connections for said motor, means including a control element movable out of agiven normal position to close one of said switches for operation'of saidmotor in one direction, an electromagnetic relay responsive upon movement of said control element out of normal position and adapted to effect closure of the other-of said reversing switches upon return of said control element to .normal position to thereby plug said motor,

and a switch operable by said motor for maintaining said relay in closed position upon return of said control element to normal position and for effecting opening of said relay upon arrest of said motor following plugging thereof,

6. In a motor controller, the combination with an electric motor, of switches for selectively establishing reverse power connections for said motor, means for selectively controlling said switches to effect plugging of said 7 motor and runnin in either direction, and means for controlhn said switches to effect inching operations 0 said motor in either di- 

